He often gives me some advice.The sentence structure is________.

Look at the boy running on the ground. Is it David?– It _______ be him. I saw him go to the teacher’s office just now.

I will let you know as soon as he _____. [ ]

Who’s singing in the next room?— It ____ be her . She has gone to New York.

Patrick is interested in animals, so he enjoys _ every Saturday working in an animal hospital.